CN100367738C - Mobile exchange center for applying 3G mobile communication system - Google Patents

Abstract

The present invention discloses a mobile switching center applied to 3G mobile communication systems, which comprises a distributed calling server (CS) subsystem, a distributed circuit media gateway (CMG) subsystem, a calling signaling gateway (CSG) subsystem and a circuit distribution unit (CDU) subsystem for calculating various kinds of routing and calling information. The mobile switching center selects an optimal routing and determines the corresponding calling server system according to routing information and corresponding parameters, time and states when applying for a circuit. The present invention is especially used for calling routing selection through circuit distribution units, and effectively utilizes the resources of calling servers and circuit media gateways to make the calling routing selection efficiency high. In addition, because the circuit media gateways in the mobile switching center of the present invention not only have circuit interfaces connected with base station systems based on circuits but also have IP interfaces connected with base station systems based on IP, the mobile switching center can be effectively compatible with the existing network facilities and can adapt to the complete IP development of future networks.

Description

Be applied to the mobile switching centre of 3G mobile communication system

Technical field

The present invention relates to a kind of mobile switching centre (MSC), particularly about a kind of mobile switching centre (MSC) that is applied in the 3G mobile communication system.

Background technology

Now, the mobile communication develop rapidly, from based on first and second third-generation mobile communication system development of voice service to 3-G (Generation Three mobile communication system) based on multimedia service, more and more higher to the requirement of mobile switching centre.Compare second generation mobile communication system, the 3-G (Generation Three mobile communication system) capacity approximately is 2-5 a times of second generation mobile communication system, the transmission information rate is brought up to 2Mbps, the transmission business except by monomedia to multimedia evolution, also expand to human-computer interaction alternately from interpersonal simultaneously, in addition, 3-G (Generation Three mobile communication system) can not only provide speech, low-speed data service etc., and has the ability that broadband data service is provided.

In mobile communication system, mobile switching centre is the core, adapts to this variation, and mobile switching centre also requires can be with the cost of economy, flexibility and reliability, lasting all existing and will have business of support.

Please refer to a kind of traditional mobile switching centre shown in Figure 1, described mobile switching centre supports large-scale circuit switching, mainly form by digital switching network (DSN) 11 and various functional module 12, these modules link to each other with network to transmit input/output signal by the pulse code modulation (pcm) link, when customer call, realize jointly that by described functional module and switching network mobile switching centre comprises control and business, inserts and be transmitted in interior repertoire.But along with the development of new technology and the appearance of new business, above-mentioned mobile switching centre can not adapt to the demand of the development and the data service of new business, therefore, ITU (International Telecommunications Union) has proposed the notion of 3G, initial 3G network, with the R99 version is example, network configuration as shown in Figure 2, described switching center comprises MSC/VLR (or GMSC/VLR, mobile switching center) 21, HLR (attaching position register) 22, SGSN (Serving GPRS Support Node) 23, the support that GGSN (Gateway GPRS Support Node) 24 has increased Packet Service, aspect circuit domain, inherit the 2G network fully, connect wireless network with MSC/VRL 21 based on circuit mode, communicate with PSTN (public switched telephone network) 26, voice service is provided; Use packet equipment,, connect wireless network, and be connected, Packet data service is provided with Internet (the Internet) 25 based on the IP mode as SGSN 23 and GGSN 24.The scheme of above-mentioned MSC because MSC externally has only circuit interface, can not be really flexible new business is provided, and be unfavorable for that future network advances to the all-IP direction.And along with the development of IP technology, the appearance of technology such as soft switch, the further evolution of network, the R5 version that proposes with 3GPP is an example, please refer to shown in Figure 3, described switching center comprises MSC server/GMSC server31, MGW (media gateway) 32 and SGW (SGW) 33, still comprise in addition as packet domain equipment such as SGSN 23 and GGSN 24, above-mentioned packet equipment links to each other with PSTN 26, MSC in the core network further is subdivided into MSC server 31 and subsystems such as MGW 32 and SGW 33, based on the thought of soft switch, be responsible for professional control by MSC server 31, and MGW 32 is responsible for professional transmission, the transmission of 33 responsible signalings of SGW, this network configuration greatly improves the tenability of following new business, and make network develop and step and go a step further to the all-IP direction, but still the problem below existing:

Though 1, mobile switching centre adopts the soft switch structure, carry out signaling control and call routing by the call server unification, when call treatment, owing to lack unified associated treatment mechanism between each call server, resource utilization is not high;

Though 2 core network inside are divided into call server and gateway device according to the thought of soft switch, but externally connection still can only be with circuit interface and related protocol, perhaps can only use packet interface (ATM or IP) processing signaling and voice service stream respectively, do not support directly connection based on the circuit base station, because mobile switching centre's external interface is single, can not make things convenient for compatible existing network facility, and be unfavorable for the development of communication network to the all-IP direction.

In sum, existing mobile switching centre also needs further to improve, to adapt to the development of future network.

Summary of the invention

For solving prior art not high problem of resource utilization when the call treatment, the invention provides a kind of mobile switching centre of the 3G of application mobile communication system, described mobile switching centre can make full use of system resource, and helps communication network and develop to all-IP.

Concrete, the mobile switching centre that is applied to the 3G mobile communication system provided by the invention, comprise distributed call server (CS) subsystem, discrete circuitry media gateway (CMG) subsystem and call signaling gateway (CSG) subsystem, in addition, also comprise circuit allocation units (CDB) subsystem, be used to add up various routes and call information; When the application circuit, select an optimum route and determine corresponding C S subsystem according to routing iinformation and relevant parameters, time and state.

Further, described circuit allocation units subsystem comprises CS polling counter, after described CS polling counter is used for selected route, the call server of this route correspondence is carried out polling to realize load sharing between each CS.

In addition, described circuit allocation units subsystem comprises that further route polling counter and route share counter, when described route polling counter is used for the route polling of call, writes down the routing number of the route of current selection; Described route is shared counter and is used in predetermined count range load counting to the route of selected different load share ratio, selects next route when this counter reduces to zero.

In addition, described circuit allocation units subsystem also comprises congested counter, be used for the selected route to Destination Point Code (DPC) is carried out congested counting, determining the congestion state of this route, and control the distribution of routing and circuit at Signaling Layer according to DPC state and congestion level.

Optimize, adopt unified IP agreement to connect between each subsystem, on described IP network, transmit signaling and business datum by IP network.

Optimize, described CMG subsystem comprises Circuit Service interface and IP operation interface, is respectively applied for base station system or other circuit-switched network and IP-based base station system or other IP network of connection based on circuit.

In addition, described CDB subsystem can be thought independent physical entity, also can be used as a stand alone software entity and is arranged in CS, VLR or the CSG subsystem.

Compared to existing technology, the present invention has following advantage:

1, among the present invention, is specifically designed to call routing, can effectively utilizes the resource of each call server and circuit message gate, make call routing efficient higher by from call server, isolating the circuit allocation units;

2, owing to circuit message gate in the mobile switching centre of the present invention, existing circuit interface is connected with base station system based on circuit, there is the IP interface to be connected again with IP-based base station system, can effective compatible existing network facility and can adapt to the development of future network all-IP.

Figure of description

Fig. 1 is the structural representation of traditional mobile switching centre;

Fig. 2 is the 3G network structural representation of R99 version;

Fig. 3 is the 3G network structural representation of R5 version;

Fig. 4 is that mobile switching centre of the present invention forms structural representation;

Fig. 5 is the physical connection schematic diagram of each several part of the present invention;

Fig. 6 is the interface schematic diagram between each part in the mobile switching centre of Fig. 4;

Fig. 7 is call proceeding 1 schematic diagram by the success of CDB control;

Fig. 8 is call proceeding 2 schematic diagrames by the success of CDB control;

Fig. 9 is call proceeding 1 schematic diagram by the failure of CDB control;

Figure 10 is 2 schematic diagrames that continue of the failed calls by CDB control;

Figure 11 is the call proceeding schematic diagram that the cellphone subscriber based on IP BSS of explanation CMG effect calls out the fixed-line subscriber of PSTN side;

Figure 12 is the transmission schematic diagram of signaling and Business Stream in the relaying tandem;

Figure 13 is the call proceeding schematic diagram that mobile switching centre of the present invention realizes the relaying tandem.

Embodiment

The present invention will be described in detail below in conjunction with accompanying drawing, the present invention is based on control and share pattern with function distribution pattern and telephone traffic/signaling traffic load that professional, transmission separate with access, utilize unified IP communication protocol and IP network, structure is supported multiple signaling/carrying and control protocol and the mobile switching centre of multiple structure externally is provided.

Concrete narration the present invention, please refer to the composition structure chart of mobile switching centre of the present invention shown in Figure 4, described mobile switching centre comprises four kinds of following functional subsystems: call server (CS) 401, circuit message gate (CMG) 402, call signaling gateway (CSG) 403 and circuit allocation units (CDB) 404.Link to each other by network 405 between described each subsystem, compare prior art, circuit allocation units 404 have been added in the mobile switching centre of the present invention, be used for global call routing control, make call routing efficient higher, the utilization of resources is more reasonable, specifies the function of each functional subsystem below:

The basic task of CS 401 is as the call signaling control appliance, under the cooperation of database facility VLR/HLR etc., finishes corresponding call signaling process and call control procedure; The management of all repeat circuit physical states and professional transmitting-receiving etc. in the CMG 402 main responsible systems, it is responsible for providing circuit interface and Circuit Switching Network (SCN), and (channel of use predefine bandwidth comes the network of bearer service, be connected as PSTN and Public Land Mobile Nerwork (PLMN) and based on the base station system of circuit, it also can provide IP-based business interface to be connected with other voip network intercommunications or IP-based base station system; CSG 403 is mainly used in the transport layer protocol of handling Signaling System Number 7 as the SGW of system, and the signaling end point (SP) or the Signaling Transfer Point function of Signaling System Number 7 is provided; And the task of CDB 404 is various routes of statistics and call information, selects an optimum route and determines corresponding C S 401 according to routing iinformation and relevant parameters, time and state when being the user applies circuit in call.

Above-mentioned functional subsystem has adopted the architecture of soft switch, business is separated with access with control, transmission, be responsible for control by CS 401, CDB 404, being responsible for medium by CSG 403, CMG 402 inserts, can upgrade separately to some function easily, the system of also being convenient to interconnects based on open soft switch agreement and other soft switch series products, adapts to the developing direction of future network.In addition, be to adopt IP network to connect between each functional subsystem among the present invention, on IP network, transmit signaling and business datum, please refer to network physical connection diagram shown in Figure 5, in mobile switching centre inside, CS 401 subsystems, CMG 402 subsystems, communicate by 100M Ethernet between CDB 404 subsystems and CSG 403 subsystems, between CSG 403 and STP 501 (Signalling Transfer Point), adopt the E1 interface to communicate, between CMG 402 and PSTN/ISDN 502 and PLMN 503, adopt the E1/STM-1 interface to communicate.In conjunction with support unified, IP basic communication protocol open, standard, system can develop and provide new business as required fast on the basis that does not change general structure; In addition, Circuit Service interface and corresponding signaling protocol that system utilizes CMG 402 to provide can be supported being connected the existing mobile communications system base station equipment and the network equipment; Because internal system connects according to IP network, therefore, system also can finish being connected IP-based mobile system equipment and other IP network equipment by IP operation interface and the corresponding protocol of CMG 402.

Further describe mobile switching centre of the present invention system configuration and relevant interface below, following network entity is according to business, control, the pattern that medium insert to separate can be divided into three planes: i.e. service plane, control plane and medium insert the plane, please refer to shown in Figure 6, top layer be the business function entity that belongs in the general mobile network system, as HLR 601, SCP 602 etc., base station system (BSS) 603 and 604 of IP-based base station systems (BSS) based on circuit belong to wireless access system, CS 401 among the present invention, CDB 404 is positioned at control plane, CMG 402 and CSG 403 belong to medium and insert the plane, and be as follows to the interface specification of each intermodule among Fig. 6 below:

Interface 1 is the signaling interface of 501 of mobile network's entity HLR outside the CS of system 401 functional units and the system, if HLR 601 is based on IP network, then the signaling interface agreement directly is MAP/SCCP/SCTP/IP; If HLR 601 is based on the circuit signaling network, then relevant MAP signaling protocol need be changed by intrasystem SGW CSG 403 and send, and promptly MAP/SCCP/M3UA/SCTP/IP is converted to MAP/SCCP/MTP3/MTP2/E1;

Interface 2 is the signaling interfaces of 502 of mobile network's entity SCP outside the CS of system 401 functional units and the system, if SCP 602 is based on IP network, then the signaling interface agreement directly is INAP/SCCP/SCTP/IP; If SCP 602 is based on the circuit signaling network, then relevant INAP signaling protocol need be changed by intrasystem SGW CSG 403 and send, and is about to INAP/SCCP/M3UA/SCTP/IP and is converted to INAP/SCCP/MTP3/MTP2/E1;

Interface 3 is signaling interfaces that native system connects IP-based base station system BSS 604, and its annexation is CS 401 to IP BSS 604, and agreement is A interface/SCCP/TCP/IP;

Interface 4 is business interfaces that native system connects IP-based base station system BSS 604, its annexation is an IP BSS access control part in the IP BSS 604 to CMG 402, agreement is the IP operation bag that has encapsulated wireless vocoder packets, is that example then is IP medium bag/EVRC bag/RTP/UDP/IP with EVRC;

Interface 5,6,7,8 interfaces 5,8 begin and stop the interface of media conversion link information alternately for CS 401 and CMG 402, interface 6,7 is the interface of control informations such as CDB 404 and CMG 402 mutual CMG 402 media resource situations, divide from agreement, interface 5,6,7,8 is MGCP/MEGACO/H.248/SCTP/UDP/IP;

Interface 9 is internal agreement interfaces of CS 401 and CDB 404 interactive media route control informations etc.;

Interface the 10, the 11st, the CMG 402 of system and the interface of the SCN of Circuit Switching Network 605 mutual circuit bearer services (PCM type business datum) they also are CMG 402 and based on the interface of the base station system BSS 603 mutual circuit bearer services (PCM type business datum) of circuit;

12 interfaces of interface are used for based on the base station system BSS 603 of circuit and the mutual A interface signaling of native system, and the A interface signaling passes to CSG 403 by this interface and changes back friendship CS401 processing;

13 interfaces of interface are used for CSG 403 and the various Signaling System Number 7 message that SS7 signaling network 606 carries based on circuit alternately, comprise transport layer control messages, various user messages etc.;

Interface 14 is Signaling System Number 7 mobile subscriber part MAP signalings of signaling such as the Signaling System Number 7 circuit User Part ISUP/TUP of mutual control station to station call between CS 401 and the CSG 403 and control services of roaming, inter-office switchover and IN service etc. etc.;

Interface 15 is in 402 of a plurality of CMG or the CMG 402, the connecting interface of different media formats stream translation, can be to wrap bi-directional conversion between circuit Media Stream pcm stream, also can be based on the conversion of the different coding form of IP bag by IP-based wireless vocoder (as EVRC).

Further specify mobile switching centre of the present invention, CS of the present invention is the core of mobile switching centre, and its basic task is as the call signaling control appliance, under the cooperation of database facility VLR/HLR etc., finishes the corresponding call processing procedure; It also provides and PSTN/ISDN net and the needed gateway relay process function of PLMN net interconnection simultaneously.Its basic function comprises:

1, call-handling capability: circuit calling controlled function, packet call controlled function, supplementary service controlled function, short message service function (SMS), voice and packet data concurrent service controlled function etc.;

2, mobile management function: comprise functions such as location registers/deletion, encryption, authentication, user area renewal;

3, hand-off process function: comprise the switching controls of different B SC in the same MSC system, the switching controls between different MS C system etc.;

4, radio resource management function;

5, webmaster/statistics/charging/Operation and Maintenance function etc.

How further specify the CS above-mentioned functions below in conjunction with the interface of narrating previously realizes:

CS 401 handles the function of A interface signaling message, the A interface is the interface between mobile switching centre and the base station controller (BSC), CS 401 can directly obtain the A interface message from IP-based base station system by interface 3 among the present invention, also can obtain the A interface message sent via the base station system based on circuit that CSG 403 transmits from CSG 403 by interface 12, CS401 handles these A interface messages and finishes such as functions such as RRM, mobile management, hand-off process and travelling carriage (MS) call managers.

Comprise interface 5,8 between CS 401 and the CMG 402, CMG 402 entities mainly are responsible for the management of all repeat circuits, vocoder resources physical state in the system and professional transmitting-receiving etc. among the present invention.Therefore, mainly finish the content such as connection, release, switch over operation of Tandem Gateway circuit and vocoder resources by interface 5,8 CS 401.

A plurality of CS 401 and grasp between the CDB 404 of overall dynamic resource route messages and carry out the resource occupation negotiations process by interface 9 interactive media route control informations etc., to obtain clear and definite resource indication, avoid resource contention, can rationally utilize media resource again simultaneously.

By interface 14 mutual IP-based Signaling System Number 7 application layer messages, comprise being used for ISUP/TUP message and MAP message that is used for exchanging visits between mobile entity and the INAP message etc. that repeat circuit is called out between CS 401 and the CSG 403.By handling ISUP/TUP message, and by the resource management function of CDB404, required repeat circuit situation during CS 401 can clearly determine to call out, and by controlling the physical operations process that corresponding C MG 402 finishes physical circuit.CS401 is by handling message such as MAP, INAP, finishes the information interaction with mobile network's entity HLR 601, SCP602 etc., and user's miscellaneous service controlled function etc. is provided.

Further, the Circuit management of concrete narration CS 401 inside, mobile switching centre represents with different routes to the circuit between the different DPC, circuit resource among each route control section CMG 402, routing configuration is on different CS 401, general repeat circuit can be by two-way relaying setting, also can be by the one-way junction setting, the advantage of two-way relaying is to improve the utilance of trunk line, this advantage is more obvious when trunk group is groupuscule, but when trunk group is very big, because the utilance of trunk line is saturated, be set to two-way relaying advantage and not obvious this moment again, therefore, can be unidirectional by part, the two-way relaying of part uses, in addition, two exchanges might take place attempt to take same circuit simultaneously, the situation of simultaneous hold (dual holding) promptly takes place, this moment, both sides can not connect, and can only force release later on by wait timeout.In order to reduce the generation of simultaneous hold situation, in each route, can adopt different circuit systems of selection, the management of repeat circuit should be supported three kinds of methods: balance-type, method 1 and method 2.In addition, when situations such as circuit breaks down, we's obturation, the other side's obturation, must be changed to corresponding circuit unavailable.Must be when the busy not busy rank of certain route changes to CDB 404 announcements, to guarantee the consistency of data in CS 401 and the CDB 404.

Following emphasis narration CDB 404 function sub-modules, CDB 404 is as the equipment of global call routing control, be to realize key equipment of the present invention, clearer describing, the operation principle of CDB 404 at first, in order to determine optimum CS 401, CDB 404 must obtain the configuring condition of circuit on each CS 401 of each route in the call routing, and generally the circuit of each route is configured at most on 16 CS 401.For the load that reduces CDB 404 and with the traffic of each module, CDB 404 do not need detailed obtain these routes on each CS 401 concrete configuration how many circuit and also have how many idle, the busy not busy rank that it only need obtain these CS401 gets final product, for example the busy not busy rank with CS 401 is made as normally, alarm and no-trunk three ranks, in addition, CDB 404 also supports two kinds of Route Selection modes: Overruning and load sharing formula.So-called Overruning is the priority according to each route, selects the low route of priority after the high route of priority is no-trunk again, and its implementation is fairly simple.And for the load sharing formula, then be in each route, to share traffic with different load sharing ratios, when the load sharing that arrives this route begins to select next route than the time.

In the load sharing formula, should support route at full capacity, promptly with the preferred some or several routes of Overruning, and by inferior other routes of selecting of load sharing formula, can also support the stand-by heat route in addition, promptly press preferred some route of load sharing formula, only just select other route whole choosing of the circuit of these routes.Concrete in order to realize above-mentioned two kinds of Route Selection modes, in CDB404 of the present invention, be provided with route polling counter and CS polling counter, when described route polling counter is used for the route polling of call, write down the routing number of the route of current selection.After described CS polling counter is used for selected route, the call server of this route correspondence is carried out polling to realize load sharing between each CS.According to the routing of load sharing formula the time, comprise that also route shares counter, be used in predetermined count range load counting to the route of selected different load share ratio, when reducing to zero, this counter selects next route.In concrete the enforcement, CS determines according to following principle:

1, CDB will obtain each CS and whether CSG loses connection immediately, if certain CS of system discovery and CSG lose connection, then to oam unit (OAM) alarm, and sends this CS of message report to CDB and loses with CSG and join, and CDB will forbid routing on this CS;

2, in signaling control aspect, CDB and CSG set up primitive contact mechanism, if CDB receives unreachable primitive of DPC or user unavailable (UPU) primitive that CSG sends, then forbid selecting the route corresponding to this DPC.

3, decide according to the Circuit management mode:

The method 1 of considering Circuit management requires to select circuit by cic circuit identification code (CIC) size order, considers so necessarily require the CIC of circuit in each CS should carry out order when configuration data.For example, the Circuit management mode of route T is method 1 and disposes circuit on CS1 and CS2, then among the CS1 CIC of route T circuit or all less than or all greater than the CIC of route T circuit among the CS2.Need to sort to these CS in CDB, when OPC＜DPC, the little CS of first arrangement CIC value selects the inferior little CS...... of CIC value again when the CS that the CIC value is little does not have circuit, and the like; For method 2 and balance-type, the busy not busy rank of choosing earlier is normal CS, and selecting rank after having selected entirely again is the CS of alarm.Owing to be provided with CS polling counter, each routing success back change counter makes it begin to select from next CS.

Further specify CDB of the present invention from Signaling Layer in the face of the dynamic control of telephone traffic below, among the present invention, between MSC and other exchange, can adopt the mode of automatic congested control (ACC) to regulate interexchange traffic, in MSC, can also adopt the mode of congested indication (CIP) to regulate the telephone traffic of all directions.

See the automatic congested control of MSC interoffice first, automatic congested control (ACC) is under the overload situation an exchange uses.MSC has two congested levels, and one is serious congestion (first order is congested) not too, and another is serious congestion (second level is congested).If reached arbitrary level of two congested levels, CDB can indicate CSG to send Automatic Congestion Control information message to contiguous office, and indicates the first order or the second level.The traffic that should be reduced to affected overload office behind the Automatic Congestion Control information message is received by contiguous office.Automatic Congestion Control information message is to be sent after receiving the clear forward signal of a circuit He before sending release guard signal by overladen office.If normal traffic load is got back to by overload office, then no longer send Automatic Congestion Control information message.Contiguous office automatically reverts to their normal condition after a predetermined time.

And, be mainly used in the information of mutual routing control between CDB and CSG for congested indication (CIP), comprising:

The congested indication of DPC: this primitive is issued CDB by CSG, after CDB receives this primitive, to adjust the congestion state of corresponding DPC, congestion state is divided into 8 grades (every grades 12.5%), and congestion state is high more, the traffic carrying capacity that allows is more little, during call routing congestion state can when being 1 grade as congestion state, will be refused a routing with one of index as route after allowing 7 routings, and then allow 7 routings, refuse a routing;

The unreachable primitive of DPC: this primitive is issued CDB by CSG, after CDB receives this primitive, will forbid that call routing arrives this DPC direction, regularly sends out DPC to CSG then and can reach inquiry primitive.CDB sends out the unreachable announcement of DPC to all CS again, and it is unreachable that the CS that has disposed this DPC is changed to DPC with the DPC state, if CS receives this announcement then stops to send out UPT to CSG under the UPU state;

DPC can reach recovery primitive: this primitive is issued CDB by CSG, after CDB receives this primitive, will return to the call routing of this DPC direction, and CDB sends out DPC to all CS again can reach the recovery announcement, and the CS that has disposed this DPC changes the DPC state normally into;

DPC can reach inquiry primitive: this primitive is issued CSG by CDB, regularly is sent to CSG when DPC is unreachable;

DPC UPU primitive: this primitive is issued CDB by CSG, after CDB receives this primitive, will forbid that call routing arrives this DPC direction, divides unavailable notice message to all CS hair Ministry of Revenue then.The CS that has disposed this DPC is changed to UPU with the DPC state, and regularly sends out a UPT test post to this DPC and whether recover available to test this DPC UP part.If CS receives any TUP﹠amp from this DPC arbitrarily; Isup message is then sent out DPC Available Reports message to CDB immediately.After CDB receives this message,, send out the DPC available notice message to all CS then with returning to the call routing of this DPC direction.CS receives that the DPC state being changed to UP after this message can use, and stops to send out UPT (User Part test) test post.

Above-mentioned primitive for getting in touch with between CSG and the CDB, after CDB receives the congested indication of the DPC of CSG, the congestion state of corresponding DPC will be adjusted, it is 8 grades (every grades 12.5%) that congestion state is divided into, congestion state is high more, the traffic carrying capacity that allows is more little, during call routing congestion state can be used one of index as route, when being 1 grade as congestion state, to after allowing 7 routings, refuse a routing, and then allow 7 routings, refuse a routing, the adjustment of described congestion state can realize that described congested counter is used for the selected route to Destination Point Code (DPC) is carried out congested counting by a congested counter in the specific implementation, determining the congestion state of this route, and according to the distribution at Signaling Layer control routing and circuit of DPC state and congestion level.

What CDB should divide affected direction is lowered traffic load (call attempt) after receiving this primitive.When CDB receives the congested indication of this DPC for the first time, increase one-level to the congestion level of influenced direction, start two time limit Tue1 and Tue2 simultaneously., in the phase the congested indication of the DPC of all the same directions of receiving is not all shown interest at Tue1, thereby made congestion level can in the very short time, not be increased to maximum.Tue1 expires but Tue2 receives that then the congested indication of DPC will increase the level 1 congestion rank again, up to highest level, restart Tue1 and Tue2 simultaneously unexpired.As Tue1 expiry (promptly during corresponding, not receiving the congested indication of DPC), then reduce the level 1 congestion rank, Tue2 restarts, unless congestion level vanishing.Tue1 and Tue2 are generally:

$\left\{\begin{array}{c}\mathrm{Tuel}=300~600\\ \mathrm{<figure-callout\; id="2"\; label="Tue"\; filenames="C0315348300271.png"\; state="\{\{state\}\}">Tue</figure-callout>}2=5~10s\end{array}\right.$

0～7 totally 8 congestion levels can be set, when congestion level is k, per 7 routings refusal k time, and make it select other route, when k=7, be equivalent to forbid routing on this route especially.

In addition, if in CS owing to reasons such as equipment obstacle can not be connected calling, CS will send to CDB and call out the reselection request letter, CDB selects an optimum route again and determines corresponding C S according to content and relevant parameters, time and the state of mail, distributes indication letter to its transtation mission circuit then.A gravity treatment counter is set in mail, makes its gravity treatment in default number of times, send routing failure letter to former CS again when still failing, and send Congestion Tone to the user.

Below the main mail that is used for routing between CS and CDB is done brief description:

Repeat circuit application request letter (CS---＞CDB): mainly carry number and routing iinformation, be used at CDB CS and Route Selection, CDB selects CS and route according to routing iinformation after receiving this mail;

Repeat circuit application response letter (CDB---＞CS): mainly carry failure cause, if in CDB to CS and route selection failure then send this mail, to former CS announcement routing failure;

Repeat circuit distribution indication letter (CDB---＞CS): mainly carry the routing number that the CDB routing obtains, CS receives that this mail is afterwards according to the route assignment circuit;

Repeat circuit call out the gravity treatment letter (CS---＞CDB): mainly carry number and routing iinformation, send out this mail when distributing failure and surpass the gravity treatment number of times in CS, CDB reselects CS and route after receiving this mail;

Routing failure letter (CS---＞CS): mainly carry failure cause.When in CS, distributing failure and having surpassed the gravity treatment number of times, send out this mail.

Below with reference to Fig. 7～Figure 10 the flow process of utilizing CDB to carry out call routing is described.

Fig. 7 is successful call routing flow process 1, and flow process is as follows:

Step 701CS sends a circuit application request to be believed to CDB, and CDB selects corresponding C S ' and route according to the routing iinformation in the described circuit application request letter; Step 702CDB distributes indication letter to selecteed corresponding C S ' transtation mission circuit; The selecteed CS ' of step 703 sends the message of routing success to the CS of original application circuit.

Fig. 8 is successful call routing flow process 2, and flow process is as follows:

Step 801CS please ask letter in the CDB transtation mission circuit, CDB is according to selection corresponding C S ' such as the routing iinformations that comprises in the described letter; The described CDB of step 802 distributes indication letter to corresponding C S ' transtation mission circuit, distribute failure as circuit, then enter step 803, corresponding C S ' distributes the failure indication letter to the CDB transtation mission circuit, CDB reselects CMG, enters step 804CDB and resends circuit distribution indication letter to CS '; Step 805 is allocated successfully, and CS ' sends the routing successful information to CS.

Fig. 9 is the call routing flow process 1 of failure, and flow process is as follows:

Step 901CS believes to CDB transtation mission circuit application request; Step 902CDB does not find available circuit, to the information of CS transtation mission circuit application failure.

Figure 10 is the call routing flow process 2 of failure, and flow process is as follows:

Step S101CS believes to CDB transtation mission circuit application request; Step S102CDB selects corresponding C S ' according to the routing iinformation in the circuit application request letter; Step S103CDB distributes indication letter to CS ' transtation mission circuit; Step S104CS ' distributes the failure letter to the CDB transtation mission circuit, and indication CDB does not have available CMG; Other CMG of step S105CDB gravity treatment, and to CS ' transtation mission circuit distribution indication letter; The CMG of the described gravity treatment of step S106 is also unavailable, and CS ' sends the routing failed message to CS.

Top emphasis has been narrated CDB, also can be equipped with physics CDB entity according to the use needs in the system, and CDB is colonized among the CS or VLR of CSG or certain appointment with form of software (being the form of software entity).

CMG below, CMG are based on the service environment of IP grouping and based on the intercommunication interface of Circuit-switched service environment, also carry out firewall functionality simultaneously where necessary.CMG mainly provides the interface that interconnects with PSTN, ISDN, PLMN and other circuit-domain network among the present invention, it by built-in 2Mbps G.703 electrical interface or 155Mbps SDH optical interface link to each other with circuit-switched network SCN, link to each other with CS, CDB by the 100Mbps Ethernet interface.CMG provides the coding and decoding function of traffic streams, as EVRC (Enhanced Variable Rate Coder), AMR (sound/modulator-demodulator plug-in card) etc., and can finish the translation of different media flows form, provides required Qos quality control method to related service.

Concrete, CMG is made up of parts such as management subsystem machine, vocoder plate, conference components plate, clock boards, the management of resource physical states such as all repeat circuits, vocoder, meeting terminal and professional transmitting-receiving etc. also have functions such as echo inhibition, double-tone transmitting-receiving, voice guidance in the main responsible system.

Execution takies or releasing operation CMG to media resource (as circuit, vocoder etc.) under the control of CS, and regularly examines the operating position of relevant resource with CS.System can design and support a plurality of CS and a plurality of CMG to work in the mode of load sharing, and a CS can manage and control a plurality of CMG.Control relation between them is mainly reflected on the data configuration, and is not subjected to the restriction (in fact each CS can communicate by letter with any one CMG in the system) of hardware annexation, therefore can be by its control membership of the online change of mode of revising data.

In the system of the present invention, manage the Dynamic Route Control relation of a plurality of CS and a plurality of CMG for convenience, be provided with occupation condition and dynamic routing configuration and the occupied information of CDB entity in order to grasp overall a plurality of CMG.So information such as the routing configuration of CMG and the main interactive media resource of CDB, fault warning.

With the main effect of a specific embodiment explanation CMG of the present invention, as shown in figure 11, a cellphone subscriber based on IP BSS calls out the fixed-line subscriber of PSTN side, may further comprise the steps below:

Step S110IP BSS receives the call request of a cellphone subscriber A, then call information is sent to CS by IP-based A interface signaling;

Step S111 CS analyzes relevant call information, and obtaining the called subscriber is the fixed-line subscriber B of PSTN side, and the route negotiations process of initiation and CDB is connected with PSTN with the circuit media resource of selecting to take which CMG;

Step S112CS notifies certain available CMG, and a circuit that takies it connects PSTN user B, and a vocoder resources notifying certain available CMG to take it is simultaneously handled the IP-based wireless speech bag that mobile phone A is sent;

Step S113 CS is according to the calling and called progress, and notice CMG (may be two or more) couples together the calling and called Media Stream, perhaps discharges a certain end.

The following describes CSG of the present invention.

CSG is the gateway device that connects Signaling System Number 7 net and IP network, and it is for providing the common signaling interface with Circuit Switching Network (PSTN/ISDN/PLMN) interconnection based on the network equipment in the IP world (as CS), makes the corresponding signaling can be in interworking between network.It also possesses firewall functionality in case of necessity.CSG both can be a part in the system, and the SGW equipment that can make a standard again uses separately.

CSG provides the 100BaseT that meets IEEE802.3 standard interface in the IP side, for the application entity in the IP network provides the No. 7 signaling network service; In PSTN (ISDN/PLMN) side, provide standard E1 interface to link to each other with existing Signaling System Number 7 net, can set up the 64Kbps of standard or the signaling link of 2Mbps with other equipment.

CSG can be MAP (MAP), TCAP (transaction capabilities), TUP/ISUP (Telephone User Part/ISDNYong Hubufen), A interface etc. Transformation Service is provided, and its basic signaling transfer principle is as shown in the table:

Signaling System Number 7 based on circuit	CSG		IP-based Signaling System Number 7 (CS)
				Call business processing/transaction	SGW		Call business processing/transaction
TUP/ISUP/SCCP	SCCP	The node IWF	TUP/ISUP/SCCP
				MTP-3	MTP-3	M3UA	M3UA
MTP-2	MTP-2	SCTP	SCTP
				MTP-1	MTP-1	IP	IP

Above-mentioned function and effect to four functional subsystems forming mobile switching centre of the present invention has been described in detail, and realizes that with mobile switching centre of the present invention the relaying tandem is that example describes its course of work below.

With reference to Figure 12～shown in Figure 13, wherein Figure 12 is the transmission schematic diagram of signaling and Business Stream in the relaying tandem, and Figure 13 is the schematic diagram of call proceeding, among Figure 12

The expression signaling flow,

The expression Business Stream is responsible for continuing of control signaling jointly by CSG, CS and CDB, is responsible for professional transmission by CMG.

With reference to Figure 13, the relaying tandem of the outer A of office and the outer B of office is finished jointly by CS1, CS2 and CDB, CMG and CSG (CMG and CSG all do not illustrate in the drawings), and flow process is as follows:

The A of the outer office of step S131 sends initial address message (IAM) to CS1; Step S132 CS1 analyzes called number according to IAM message and determines that described called number is outer office Subscriber Number, is determined to some the routes and the relevant parameter of target office in the prefix mark sheet, and believes to CDB transtation mission circuit application request; Step S133CDB selects an optimum route T and determines corresponding C S2 according to circuit application request letter and correlation behavior from these routes, distribute indication letter to the CS2 Power Generation Road then; Step S134CS2 distributes an idle circuit in route T, outwards the B of office sends initial address message (IAM) then, sends routing at step S135 to CS1 simultaneously and successfully believes; The A of the outer office of step S136 sends address perfect information (ACM) to CS2; The step S137 called state free time, the CS1 outwards A of office sends ACM message; Step S138 called party answer, the outer B of office sends response message (ANM) to CS2; The step S139CS1 outwards A of office sends ANM, and outer A of office and the outer B of office set up conversation.

When calling out a side be the mobile subscriber, the opposing party be fix or MSC on outbound call the time, also need base station transceiver BTS, base station controller BSC and CS and CSG to finish continuing of signaling jointly.BTS and BSC are used for wireless access, and CDB carries out call routing, distribute a circuit on certain CMG to be used for striking out by CS then.On business, need on CMG, distribute a vocoder by CS, be used to handle from the voice packet of BTS and the speech conversion between the last circuit switching of CMG, the course of work is similar to above-mentioned relaying tandem, repeats no more here.

In addition, be office call if call out, and the vocoder of calling both sides is identical, then controls continuing of signaling, by BST and the professional transmission of BSC control by BST, BSC and CS.And for office call, and the vocoder types of calling both sides is not simultaneously, by continuing of BST, BSC and CMG control signaling,, also need to be used for conversion between the voice packet of different vocoder types at vocoder of application on the CMG by BST, BSC and the professional transmission of CMG control.

The above only is the preferred embodiments of the present invention, and is non-so promptly limit to interest field of the present invention, and the equivalence that all utilizations specification of the present invention and accompanying drawing content are done changes, and all reason is with being contained in the claim scope of the present invention.

Claims (8)

1. mobile switching centre that is applied to the 3G mobile communication system, comprise distributed call server CS subsystem, be used for call signaling control, finishing call signaling handles and call control procedure, discrete circuitry media gateway CMG subsystem, comprise Circuit Service interface and IP operation interface, be used for the management and the professional transmitting-receiving of repeat circuit physical state, be responsible for providing the network of bearer service, call signaling gateway CSG subsystem, be used to provide signaling end point or Signalling Transfer Point, it is characterized in that:

Also comprise circuit allocation units CDB subsystem, be used to obtain the configuring condition of circuit on each CS and the busy not busy rank of described CS of each route, add up various routes and call information; It is high and be not in the route of no-trunk state to select a priority according to routing iinformation and relevant parameters, time and state in application during circuit, or select a route that does not reach default negative what share ratio, and definite corresponding C S subsystem according to routing iinformation and relevant parameters, time and state; Adopt unified IP agreement to connect between described each subsystem, on described IP network, transmit signaling and business datum by IP network.

2. mobile switching centre according to claim 1 is characterized in that:

Described circuit allocation units subsystem comprises CS polling counter, after described CS polling counter is used for selected route, the call server of this route correspondence is carried out polling to realize load sharing between each CS.

3. mobile switching centre according to claim 1 and 2 is characterized in that:

Described circuit allocation units subsystem comprises that further route polling counter and route share counter, when described route polling counter is used for the route polling of call, writes down the routing number of the route of current selection; Described route is shared counter and is used in predetermined count range load counting to the route of selected different load share ratio, selects next route when this counter reduces to zero.

4. mobile switching centre according to claim 3 is characterized in that:

Described circuit allocation units subsystem further comprises congested counter, be used for the selected route to Destination Point Code DPC is carried out congested counting, determining the congestion state of this route, and according to the distribution at Signaling Layer control routing and circuit of DPC state and congestion level.

5. mobile switching centre according to claim 1 is characterized in that:

Described CMG subsystem comprises Circuit Service interface and IP operation interface, and described Circuit Service interface is used to connect base station system or other circuit-switched networks based on circuit, and described IP operation interface is used to connect IP-based base station system or other IP network.

6. mobile switching centre according to claim 1 is characterized in that: described CDB subsystem is a physical entity.

7. mobile switching centre according to claim 1 is characterized in that: described CDB subsystem is a software entity.

8. mobile switching centre according to claim 7 is characterized in that: described CDB software entity is arranged among CS, VLR or the CSG.

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